The Ultimate Weight Loss Cause (Hormones vs. Calories) | Jason Fung

today i'm going to talk about weight loss is it a problem of hormones or is it a problem of calories and this is a really important question because if you focus on the wrong issue your strategy is not going to work and you're not going to be able to lose weight and it's coming right up hey big announcement we've got merchandise featuring the fasting method you just have to click down below on the merchandise shelf we've got hoodies we've got t-shirts we've got pants and we've got glasses check them out [Music] how does the body gain body fat it's a good question and it's not one that we often think about because we think we already know the answer it's just about calories isn't it if you look into the science of obesity it's much more complicated and there's in fact two competing theories that have been around for over a hundred years in the new england journal of medicine in 1953 dr pennington had already identified that there's two distinct lines that of intermediary metabolism and that of energy exchange in other words there was a debate even back then of whether obesity is a hormonal problem or is it a caloric problem i'm going to start with the evidence that it's a caloric problem because it's the one that most of us are more familiar with we've all heard it body fat is simply calories in minus calories out and you can look at studies such as this one which was from the washington post which shows that over the past 40 50 years we've eaten more calories from 2027 to 2507 and that's coincided with an increase in obesity even as the percentage of carbohydrates and fats in the diets have remained relatively stable and this is certainly true it however does not mean that simply cutting your calories is going to lead to weight loss for that we use the randomized control trial we take two groups of people we give them different interventions and see if they can lose weight the biggest of these studies was the women's health initiative which took almost 50 000 women and randomized them to a low-fat calorie restricted diet compared to their standard diet and what you can see is that over eight years these women did in fact reduce the number of calories that they consumed as well as increase the amount of exergs size by about 10 percent as measured by mets which are metabolic equivalents however this did not translate into meaningful weight differences the weight difference between the two groups were in fact less than a kilogram over eight years it was hardly the only study to show the lack of efficacy of restricting calories alone this study from the journal of the american diabetic association in 2007 reviewed over 80 studies to see what effect this type of advice would have turns out that over the two-year span that advice produced virtually no weight loss the advice to exercise also produce very little weight loss if you were to put people on a very stringent diet or diet plus exercise it did have some weight loss perhaps about five kilos in the first six months but after six months there was a slow regaining of the weight so this diet did not lead to further weight loss as the calories theory would suggest but in fact it simply plateaued or regained this 2001 study from the american journal of clinical nutrition shows really the same thing it's a meta-analysis where they take all the studies that had been published to that point on calorie restricted diets put them all together and estimated what effect it would have if you did a low calorie diet which is sort of the standard advice that physicians would give over five years you might have an average weight loss of about three kilograms around six pounds a very low calorie diet which is somewhere on the order of eight hundred to a thousand calories is a little bit more effective at seven kilos but still over time that weight was regained it had its most effect at year one and every year it was losing its effect steadily even as people continue to follow that diet you might say that perhaps the weight is not a big issue but they were healthier and that's the question that the lookahead study asked in 2013 they took people and they got them to lose weight with a very strict diet as little as a thousand calories a day plus medications to make sure that that weight stayed off even then it still had its best effect at one year with slow regaining of weight thereafter still only about 5 kilos or just over 10 pounds even with the strictest diet and medications but what happened to their health did they have less heart attacks strokes did they die less often unfortunately after over 10 years of study there's no difference so these people who are forced onto a low-calorie diet sometimes with medications to help were not actually much healthier and only weighed a little bit less than their peers who did nothing at all if calorie restriction doesn't cause weight loss there's another part to this theory can overfeeding cause weight gain in the long term and that seems to be a slam dunk it seems to be easy to say if i just eat more i'm going to gain weight in the 1960s this was the experiments done by dr ethan sims who thought he should be able to force people to gain weight he started off with college students thinking that he would pay them they would gain weight and he would study what happened to their bodies unfortunately most of them were unable to gain weight so he instead switched to vermont state prisoners where he could control their diet as well as their exercise and in some cases he would have to feed them up to eight or ten thousand calories a day to get them to gain weight a huge amount much more than we normally do after the experiment was done those people simply lost all that weight so reducing calories is not a very good way to make somebody lose weight and over feeding calories is not an especially good way to make them gain weight this was also shown in this 1992 study which showed that you could force people's body weight up but as soon as you stopped force feeding them they would immediately revert back to their usual weight if calories is not the major reason we gain or lose body weight then what is the other major theory is that is controlled by hormones if we look at the energy balance equation that is body fat equals calories and calories out we can say perhaps the controlling factor is the hormones which controls our percentage of body fat which leads us to more calories in or less calories out depending on if we want to gain or lose body fat so body fat is always about calories in calories out but it's not always under conscious control and that's the point the hormonal and the caloric theory don't actually contradict each other calories is the currency which it uses but the question is not whether or not the body is taking more calories in versus calories out as it gains weight the question is what is controlling the calories in versus calories out you might say that it's all depends on exercise and what you eat so it's all under your conscious control but it's simply not true if you look at the mean determinant of how much you eat which is calories in it is whether you're hungry if you're hungry you're going to eat more if you're not hungry you're going to eat less so therefore the hormonal control of hunger is what is in fact the most important determinant of calories in not willpower for calories out we think of it as exercise but in fact it's basal metabolic rate at rest with no exercise our bodies are often using 2000 calories if we walk for 45 minutes it uses maybe an extra 100 or 150 calories so the major reason that people use up calories and this is not just for the muscles but also for the heart the lungs liver is not exercise but metabolic rate which is controlled by hormones so calories in calories out is determined by hunger and basal metabolic rate neither of which is under your control you can't decide to be less hungry you can't decide to burn more calories through your metabolic rate those are controlled by hormones the hormonal theory supersedes the caloric theory because the hormones are what determines the calories body fat equals calories in calories out is very simplistic thinking what you have to do is go beyond that and say why why are we eating more calories if you go back to this initial study where you see that americans are eating almost 20 percent more calories the question is not whether they're eating more calories the question is why they're eating more calories and it's the hormones that have made that determination and how do you control those hormones it's the foods that we eat and how often we eat them certain foods are going to stimulate certain hormones for example you eat a slice of white bread insulin goes up you eat an egg insulin doesn't go up so the food is actually instructions to our body as to what to do with it and also how to adjust our body weight up or down so it's not the calories that's important it's the hormones behind that if you eat a hundred calories of cookies versus a hundred calories of broccoli the hormonal response in our bodies are completely different so the fattening effect is completely different therefore what you have to do is think one step ahead of the calories and go beyond that and say what is controlling that and by doing that you'll be much more successful in trying to lose weight thanks for watching i hope you learned something if you did maybe share it with a friend you might be able to help them as well and if you could do me a favor and just hit that like button down there it'll help people find this video see you next week

Channel: Jason Fung

Views: 215,183

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Id: wPGGOhsK29o

Length: 12min 43sec (763 seconds)

Published: Sun Jul 11 2021